(1) Field of the Invention
The present invention relates to a maxillofacial orthodontic appliance that can be used preferably for correcting malocclusion.
(2) Description of Related Art
Conventionally, various methods have been used for correcting malocclusion.
In the case of maxillary protrusion (so-called, prominent teeth) caused by malocclusion, it is common to adopt a treatment in which the maxillary dental arch is retracted (moved distally). On the other hand, in a case of mandibular protrusion (so-called, protruding lower lip and jaw), it is common to adopt a treatment in which the mandibular dental arch is retracted (moved distally).
In the following, an explanation will be given on a typical example of a distal movement treatment of teeth, referring to FIG. 7. FIG. 7(A) to FIG. 7(C) are all diagrams illustrating teeth of a maxilla from within an oral cavity.
When a crowding of anterior teeth T1, T2, T3 is seen, as shown in FIG. 7(A), it is common to take a treatment for correcting the dental arch in which spaces G4, G4 are secured by extracting the fourth teeth (first premolars) T4, T4 (see FIG. 7(B)) and then the third teeth (canines) T3, T3, the second teeth (lateral incisors) T2, T2 and the first teeth (central incisors) T1, T1 are moved distally.
Incidentally, though a distal movement treatment of maxillary teeth was explained above, a distal movement treatment of mandibular teeth is almost the same as the method described above referring to FIG. 7. However, in a distal movement treatment of mandibular teeth, the fifth teeth of the mandible (mandibular second premolars) may be extracted.
In such a method, the distance by which the dental arch can be moved is small and thus a severe case of malocclusion can not be treated. Therefore, according to the circumstances, a surgical treatment including amputation of bones may be carried out.
The above-described method of orthodontic treatment is generally known. Moreover, appliances used for such an orthodontic treatment are also widely known. An example of such kind of appliance is disclosed in Patent Document 1 below.
However, even with an orthodontic treatment by means of a distal movement, such as described above, or a surgical treatment, malocclusion relapses after several years have passed.
Most of the researchers have been conventionally supported the hypothesis that such relapses occur for the reason that malocclusion is hereditary.
Specifically speaking, by such an inheritance-based theory, an explanation that a genetic cause will induce relapse of irregular teeth and malocclusion even with a distal movement treatment or a surgical treatment of teeth will be given.
[Patent Document 1] Japanese Patent Laid-Open Publication (Kokai) No. 2006-42963